This invention relates to a method of treating a permeable structure such as a subterranean formation using nitrogen-containing cationic perfluorinated compounds in order to stabilize, in the structure, migrating fines such as silica fines.
The recovery of fluids such as oil or gas or combinations thereof has been troublesome in areas where a subterranean formation is composed of one or more layers or zones which contain migrating fines such as silica, iron minerals, and alkaline earth metal carbonates. These fines tend to move or migrate to the well bore during the recovery of formation fluids from the particular layers or zones and frequently the migrating fines block the passageways leading to the well bore. The movement or migration of fines to the well bore is a particular problem when the fines are contacted with water foreign to the formation. Plugging or materially impairing the flow of the formation fluids towards the well bore results in a loss of these fluids to the producer and decreases the rate of hydrocarbon recovery from the well which may cause the well to be shut down because it is economically unattractive to produce therefrom. An additional adverse factor resulting from the movement of the fines towards the well bore is that they are often carried along with the formation fluids to the well bore and pass through pipes, pumps, etc., being used to recover the formation fluids to the surface with resulting damage to the moving parts as the fines are very abrasive.
Secondary and tertiary methods of recovering hydrocarbons from a subterranean formation are well known. In general, such a method involves introducing a fluid, such as water, steam, etc., into one or more injection wells which penetrate the formation and forcing the fluid toward one or more offset producing wells. Migrating fine particles during such an operation can decrease the permeability of the formation which may cause a decrease in the rate in which fluid can be injected into the formation which results in a decrease in the rate of hydrocarbon production at the offset production wells.
Migrating fine particles are frequently encountered during acidizing or fracturing operations and during sand consolidation operations. The presence of migrating fine particles during these operations can result in a decrease in the permeability of the formation which is being treated.
Gravel packing is a widely practiced method of preventing the production of sand from poorly consolidated formations. The migration of fine particles into the gravel pack can greatly reduce the permeability of the gravel pack. This can result in a decrease in the rate of production of hydrocarbons from the formation.
Consequently, in efforts to overcome these problems, various methods have been developed for treating a subterranean formation in order to stabilize portions of the formation containing migrating fines. For instance, U.S. Pat. Nos. 4,366,071; 4,366,072; 4,366,073; 4,366,074; 4,374,739; 4,460,483, and 4,462,718 disclose the use of organic polycationic polymers to prevent or reduce the ill effects of swelling clays or migrating fines or combinations thereof in subterranean formations. These patents are assigned to the assignee of the present invention and are hereby incorporated by reference.
Furthermore, nitrogen-containing cationic perfluorinated compounds have been used in the past in relatively unrelated applications. U.S. Pat. Nos. 4,408,043; 4,404,377; and 4,377,710 disclose that nitrogen-containing cationic perfluorinated compounds have uses similar to those of commercial fluorocarbon surfactants and show utility in areas such as hydrocarbon emulsifiers in water, flotation aids, the treatment of porous substrates such as leather, wood, porous plastics and various natural or synthetic textiles to modify surface characteristics, oil and water repellents, general surfactants, additives for dry powder extinguisher compositions, antimicrobials, soil repellents, additives for polishes and waxes, corrosion inhibitors for oils and lubricants, foaming and wetting agents, and emulsifier and leveling agents for dye preparations.
U.S. Pat. No. 4,425,242, which is assigned to the assignee of the present invention and is hereby incorporated by reference, discloses the use of nitrogen-containing cationic perfluorinated compounds in a subterranean formation to reduce wetting by hydrocarbons and water of the surfaces of the subterranean formation.
U.S. Pat. No. 4,440,653, which is assigned to the assignee of the present invention and is hereby incorporated by reference, discloses the use of nitrogen-containing cationic perfluorinated compounds to prepare highly stable alcohol foams.
The present invention provides a method of stabilizing fines, such as silica fines, within a consolidated structure, such a subterranean formation, using nitrogen-containing cationic perfluorinated compounds which are effective in reducing the migration of fine particles in the consolidated structure.